Touch screen display user interfaces that rely on gestural input from users are being used in myriad systems and environments. One of the motivations for using such interfaces is to offer an intuitive short cut to system functionality through physical gestures performed on the touch screen surface. Additionally, a user can invoke a control function from anywhere on the sensitive portion of the touch screen display. Hence, a dedicated button, knob, or other user interface element located in a fixed location or in a menu hierarchy is not required. This increases the total available touch screen area for displaying actual information contents and reducing the time on task.
Although gestural touch screen display user interfaces can be both attractive and intuitive to a user, these interfaces can exhibit certain drawbacks. For example, in an environment where multiple physical and mental tasks may be performed by a user, such as an aircraft pilot, a crane operator, a vehicle driver, or a soldier, a gestural touch screen display user interface can increase physical/cognitive workload, degrade user experience, and/or reduce operational margin and usability of the interface. More specifically, mandatory complete and long gestural interaction with the interface can be more difficult than, for example, a single click of a mouse button or a single tap on a touch screen. This could further add to the physical workload if a user needs to operate a gestural touch screen display user interface repetitively, e.g. multiple pinch in/out gestures for zooming maps, multiple swipe up/down gestures for scrolling a list, etc. When experiencing turbulence, while on rough roads or seas, vehicle operators could face additional difficulty in inputting complete gestures. It is possible that a vehicle operator would be unable to input the correct and complete gesture, thereby degrading the user experience and reducing usability of the gestural touch screen user interface in such unstable conditions. Furthermore, some operators might naturally strive for inputting perfect and complete gesture even in calm situations. This could undesirably increase the head-down time of such operators.
Hence, there is a need for a gestural touch screen display user interface that does not rely on mandatory complete and long gestural interactions for implementing a control function. The present invention addresses at least this need.